The use of crosslinked rubber particles (so-called rubber gels) as fillers with a reinforcing action in combination with un-crosslinked rubbers for the production of vulcanizates is known. The use of such rubber gels as fillers for the production of rubber vulcanizates improves in particular the tensile modulus at 300% elongation, the elongation at break, the tensile strength and also the abrasion of the vulcanizates and the molded bodies produced from them e.g. tires. In addition, vulcanizates to which rubber gels based on polybutadiene are added, have low impact resilience (low hysteresis losses) over a wide temperature range. Rubber gels based on styrene/butadiene rubbers are characterized by low impact resilience at room temperature (good Wet-slip behavior) and high impact resilience at 70° C. (low rolling resistance).
As a result of the improvements in properties achieved by using rubber gels for the production of vulcanizates or rubber molded bodies, there has been no shortage of attempts to continuously improve and optimize the rubber gels known, in order to increase still further their physical effect on the production of vulcanizates and rubber molded bodies.
The rubber molded bodies or rubber vulcanizates produced with the crosslinked rubber particles according to the present invention, modified by secondary amino-(meth)-acrylate groups, are have improved mechanical properties, an improvement in the product of the tensile modulus at 300% elongation and elongation at break (σ300×εb), when multifunctional sulfonyl azides are used for crosslinking in addition to the conventional chemicals for sulfur crosslinking, and that it is possible in mixtures containing silica, to reduce the quantity of bis-(triethoxysilyl-propyl-3)-tetrasulfide by using multifunctional sulfonyl azides without losses in the product σ300×εb.
The present invention improves the physical properties described of the blends or vulcanizates and molded bodies produced with rubber gels, in particular the product of the tensile modulus at 300% elongation and the elongation at break (σ300×εb) and also to ensure that rubber blends containing gel and silica and the vulcanizates produced from them can be accessed economically, are toxicologically safe and also that good coupling of the rubber gels and the silicas to the rubber matrix is assured, in combination with rapid and economical vulcanization.
It was found, that the rubber gels according to the invention described in more detail below, which are modified by secondary amino-(meth)-acrylate groups, help to achieve the improved physical properties described, as it was found, surprisingly, that with the rubber gels modified according to the present invention, it is even possible, when using light fillers such as silicas, to reduce the quantity of silane coupling agents considerably, without having a negative impact on the physical properties of the vulcanizates.